Question

Condensed matter and dense gases emit electromagnetic radiation

Answer 1

Atomic Spectra. All condensed matter (solids, liquids, and dense gases) emit electromagnetic radiation at all temperatures. Also, this radiation has a continuous distribution of several wavelengths with different intensities. This is caused by oscillating atoms and molecules and their interaction with the neighbours.

Answer 2

Answer:

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All condensed matter (solids, liquids, and dense gases) emit electromagnetic radiation at all temperatures. Also, this radiation has a continuous distribution of several wavelengths with different intensities. This is caused by oscillating atoms and molecules and their interaction with the neighbours. In the early nineteenth century, it was established that each element is associated with a characteristic spectrum of radiation, known as Atomic Spectra. Hence, this suggests an intimate relationship between the internal structure of an atom and the spectrum emitted by it.

When an atomic gas or vapour is excited under low pressure by passing an electric current through it, the spectrum of the emitted radiation has specific wavelengths. It is important to note that, such a spectrum consists of bright lines on a dark background. This is an emission line spectrum. Here is an emission line spectrum of hydrogen gas:

The emission line spectra work as a ‘fingerprint’ for identification of the gas. Also, on passing a white light through the gas, the transmitted light shows some dark lines in the spectrum. These lines correspond to those wavelengths that are found in the emission line spectra of the gas. This is the absorption spectrum of the material of the gas.